The Trial That Changed the Debate
A six-month trial involving 61 UK companies and 2,900 employees found that moving to a four-day work week — with no reduction in pay — produced a 20% average gain in productivity and zero revenue losses across all participating organisations. The findings, published in the journal Nature Human Behaviour, are the largest study of the four-day week ever conducted.
What Changed
- Sick days fell by 65% across participating firms.
- Staff turnover dropped by 57%.
- Revenue across the trial group grew by an average of 1.4%.
- 92% of companies said they intend to make the change permanent.
The Sceptic's Argument
Critics note the self-selecting nature of the trial — companies that volunteered were already likely to be progressive employers. Manufacturing, healthcare, and retail sectors may face structural barriers to adoption that knowledge-work companies do not.
"The trial is not proof that four days works for every industry. But it is proof that the assumption it can't work is simply wrong," said the lead researcher.
